JP2013109081A - Inverted microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverted microscope allowing an ultrawide-field observation despite constituting an ocular optical system and a binocular lens barrel short, light and inexpensive.SOLUTION: An inverted microscope 1 comprises: an objective optical system 2 that collects light from a specimen A; an image-forming optical system 3 that images the light from the specimen A that has been collected by the objective optical system 2 to form an intermediate image; a relay optical system 6 that relays the intermediate image B of the specimen A formed by the image-forming optical system 3; a binocular lens barrel 5 that splits the light from the relay optical system 6; a pair of ocular optical systems 4 that images, in a magnified manner, the intermediate images that have been split by the binocular lens barrel 5 on eyes E of an observer as virtual images. The inverted microscope 1 satisfies the following conditional expressions: (1) K=(Fntl/Ftl)×βRL, (2) Fne=Fe×K, and (3) 0.3<K<0.9.

Description

  The present invention relates to an inverted microscope.

Conventionally, an ultra-wide-field eyepiece for a microscope is known (see, for example, Patent Document 1).
This eyepiece is an ultra-wide-field eyepiece having a magnification of 10 and a field number of 26.5.

Japanese Patent No. 3250739

  However, the eyepiece of Patent Document 1 has a disadvantage that the lens diameter is large, the total length is long, and the number of lenses is large, so that the eyepiece itself is enlarged. In order to achieve the number of fields of 26.5, the effective range of the cross section perpendicular to the optical axis must be 26.5 mm or more in diameter as a prism in the binocular tube connected to the eyepiece. The prism to be used must have an outer shape of 30 mm square, and the binocular tube is large, heavy, and expensive.

  The present invention has been made in view of the above-described circumstances, and provides an inverted microscope capable of observing an ultra-wide field of view while configuring an eyepiece optical system and a binocular tube short, light and inexpensive. It is an object.

In order to achieve the above object, the present invention provides the following means.
The present invention includes an objective optical system that collects light from a sample, an imaging optical system that forms light from the sample collected by the objective optical system as an intermediate image, and the imaging optical system. A relay optical system for relaying the imaged intermediate image, a light branching part for branching light from the relay optical system, and a virtual image in the observer's eye by enlarging the intermediate image branched by the light branching part And an eyepiece optical system that forms an image as an inverted microscope that satisfies the following conditional expression.
K = (Fntl / Ftl) × βRL (1)
Fne = Fe × K (2)
0.3 <K <0.9 (3)
Here, K: coefficient, Fntl: focal length of the imaging optical system, Ftl: focal length of the reference imaging optical system with a magnification of 1, βRL: magnification of the relay optical system, Fne: eyepiece optical system The focal length of the reference eyepiece optical system in an inverted microscope including the reference imaging optical system and the reference objective optical system.

  According to the present invention, compared with an inverted microscope having a reference imaging optical system and a reference eyepiece optical system with a magnification of 1 ×, the focal length of the eyepiece optical system is shortened to increase the magnification, and image formation is performed at the same rate. The total magnification of other optical systems including the optical system and the relay optical system is reduced. By doing so, the magnification of the eyepiece optical system can be increased and the number of fields of view can be made substantially the same without changing the overall magnification of the inverted microscope. The fact that the number of fields of view is substantially the same means that the field of view is the same even if the magnification of the reference eyepiece optical system and the magnification of the eyepiece optical system are different. At this time, the total magnification of the other optical systems including the imaging optical system and the relay optical system is reduced, so the diameter of the light beam passing through the prism in the binocular tube is reduced, the prism is downsized, and the binocular tube is downsized. can do. When K ≦ 0.3, the focal length of the imaging optical system becomes too short, and it becomes impossible to sufficiently secure the air-converted optical path length before the left and right branching in the binocular tube, or the magnification of the relay optical system becomes too small. Design becomes difficult. If Kt ≧ 0.9, the prism cannot be substantially reduced in size.

In the said invention, it is preferable to satisfy the following conditional expressions.
15 <FN <22 (4)
Here, FN is the number of fields of view of the eyepiece optical system.

Moreover, in the said invention, it is preferable to satisfy the following conditional expressions.
0.45 <K (5)
Here, FN is the number of fields of view of the eyepiece optical system.
By doing so, the focal length of the eyepiece optical system can be increased compared to the case where K ≦ 0.45, and the coma aberration characteristic of the eyepiece optical system is improved.

Moreover, in the said invention, it is preferable to satisfy the following conditions.
140 <Fntl <210 (6)
0.55 <βRL <1.1 (7)
8 <Fne <23 (8)

  According to the present invention, it is possible to provide an inverted microscope capable of observing an ultra-wide field of view while configuring the eyepiece optical system and the binocular tube to be short, light and inexpensive.

It is a figure which shows the inverted microscope which concerns on the 1st Embodiment of this invention. It is a figure which shows the modification of the inverted microscope which concerns on the 1st Embodiment of this invention. (A) It is a figure which shows the inverted microscope which concerns on the 1st Embodiment of this invention, (b) The conventional inverted microscope. It is a figure which shows the lens structure which concerns on 1st Example of the inverted microscope of FIG. FIG. 5 is an aberration diagram of the inverted microscope of FIG. 4. It is a figure which shows the lens structure which concerns on 2nd Example of the inverted microscope of FIG. FIG. 7 is an aberration diagram of the inverted microscope of FIG. 6.

(First embodiment)
An inverted microscope 1 according to a first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the inverted microscope 1 according to the present embodiment irradiates the sample A via the objective optical system 2 disposed below the stage S on which the sample A is mounted, and the objective optical system 2. An illumination optical system 7 for supplying illumination light, an imaging optical system 3 for condensing the light from the sample A consisting of an infinite light beam to form an intermediate image, and an image formed by the imaging optical system 3 and a mirror 11 Relay optical system 6 that relays the intermediate image reflected in the horizontal direction, binocular tube 5 (light branching section) that branches the intermediate image relayed by relay optical system 6 into two, and the intermediate image of sample A is enlarged And an eyepiece optical system 4 that forms images at positions where the retinas of both eyes E of the observer are arranged.

The objective optical system 2 condenses the light emitted from the sample A and guides it vertically downward as a substantially infinite light beam.
The illumination optical system 7 includes a light source 8 such as a mercury lamp that generates illumination light, a condensing optical system 9 that condenses the illumination light from the light source 8, and the illumination light collected by the condensing optical system 9 as an object. And a dichroic mirror 10 that deflects in a direction along the optical axis OA of the optical system 2. The focal position of the condensing optical system 7 coincides with the rear focal position of the objective optical system 2 so that illumination light composed of substantially parallel light can be irradiated onto the sample A.

  The relay optical system 6 relays an intermediate image formed by the imaging optical system 3 and reflected in the horizontal direction by the mirror 11, and includes a plurality of relay lenses 12 to 15. Further, a mirror 16 is provided between the relay lens 13 and the relay lens 14 to reflect the horizontal light flux in the vertical direction.

The binocular tube 5 includes a prism 17 that reflects the light beam that has passed through the relay optical system 6 in a direction inclined obliquely upward, and a binocular branching prism 18 that branches the light reflected by the prism 17 into two. .
The eyepiece optical system 4 enlarges the intermediate image of the sample A relayed by the relay optical system 6 and forms images at positions where the retinas of the eyes B of the observer are arranged. The eyepiece optical system 4 is a pair of optical systems corresponding to each of the two light beams branched by the binocular branching prism 18.

  According to the inverted microscope 1 according to the present embodiment, the illumination light emitted from the light source 8 of the illumination optical system 7 is condensed by the condensing optical system 9 and then the optical axis of the objective optical system 2 by the dichroic mirror 10. It is deflected in a direction along OA. Then, the illumination light is irradiated by the objective optical system 2 onto the sample A disposed on the stage S vertically above the objective optical system 3.

  The light emitted downward from the sample A is collected by the objective optical system 2 and becomes a substantially infinite light beam directed vertically downward, passes through the dichroic mirror 10 and enters the eyepiece optical system 3. The light beam incident on the eyepiece optical system 3 is reflected from the vertical direction to the horizontal direction by the mirror 11 and enters the relay lens 12 of the relay optical system 6. The relay optical system 6 reflects the light beam incident in the horizontal direction vertically upward by the mirror 16 and makes the light beam enter the binocular tube 5. The binocular tube 5 branches the light beam reflected by the prism 17 into two by the binocular branching prism 18. Then, the intermediate image of the sample A is magnified by the pair of eyepiece optical systems 4 and formed at a position where the retinas of the eyes B of the observer are arranged. The observer can observe the image of the sample A in detail by arranging both eyes E at the focal position of the eyepiece optical system 4.

  The inverted microscope 1 shown in FIG. 1 changes the direction of the light beam at two locations of the mirror 11 and the mirror 16, but adopts the modification shown in FIG. 2 that changes the direction of the light beam at one location of the mirror 11. May be. In the relay optical system 6 shown in FIG. 2, the mirror 16, the relay lens 14, and the relay lens 15 are deleted from the relay optical system 6 shown in FIG. Moreover, in the binocular tube 5 shown in FIG. 2, the prism 17 is deleted from the binocular tube 5 shown in FIG. 2, the same reference numerals as those in FIG. 1 are the same as those in FIG. 1, and description thereof is omitted.

Next, the microscope optical system of the inverted microscope 1 according to the present embodiment will be described in comparison with a reference example.
As shown in FIG. 3A, the microscope optical system of the inverted microscope 1 according to the present embodiment is focused by the objective optical system 2 that collects the light from the sample A and the objective optical system 2. An image forming optical system 3 that forms light from the sample A as an intermediate image B, a relay optical system 6 that relays the intermediate image B formed by the image forming optical system 3, and a relay optical system 6 A binocular tube 5 (light branching portion) that branches light into two and an intermediate image C of the sample A branched by the binocular tube 5 (light branching portion) are magnified, and a virtual image with a viewing angle 2ω is observed in the observer's eyes E And an eyepiece optical system 4 that forms an image as D.

FIG. 3B shows, as a reference example, a reference objective optical system 2 ′, a reference imaging optical system 3 ′ having a magnification of 1 ×, a reference eyepiece optical system 4 ′ having a magnification of 10 ×, a binocular tube 5 ′, A microscope optical system of an inverted microscope 1 ′ having a reference relay optical system 6 ′ having a magnification of 1 is shown.
In FIG. 3, each optical system is shown as a single lens, but in actuality, each optical system is constituted by a plurality of lenses.

The inverted microscope 1 according to the present embodiment satisfies the following conditional expression.
K = (Fntl / Ftl) × βRL (1)
Fne = Fe × K (2)
0.3 <K <0.9 (3)
Here, K: coefficient, Fntl: focal length of the imaging optical system 3, Ftl: focal length of the reference imaging optical system having a magnification of 1, βRL: magnification of the relay optical system, Fne: eyepiece optical system 4 Focal length, Fe: focal length of the reference eyepiece optical system 4 ′ in the inverted microscope 1 ′ having the reference imaging optical system 3 ′ and the reference objective optical system 2 ′

  According to the inverted microscope 1 according to the present embodiment configured as described above, when the light from the sample A is collected by the objective optical system 2 and is incident on the imaging optical system 3 as substantially parallel light, the image is formed. After being focused by the optical system 3, the intermediate image B is formed and then incident on the relay optical system 6, and further incident on the eyepiece optical system 4 via the binocular tube 5.

  In this case, the inverted microscope 1 according to the present embodiment includes a reference imaging optical system 3 ′ having a magnification of 1 ×, a reference relay optical system 6 ′ having a magnification of 1 ×, and a reference eyepiece optical system 4 ′ having a magnification of 10 ×. Compared with the inverted microscope 1 ', the focal length Fne of the eyepiece optical system 4 is shortened to increase the magnification. Then, the total magnification of the objective optical system 2, the imaging optical system 3, and the relay optical system 6 is reduced at the same ratio as the ratio of increasing the magnification of the eyepiece optical system 4. As a result, the number of fields of view of the eyepiece optical system 4 can be made substantially the same without changing the overall magnification of the inverted microscope 1 '. Here, in the present embodiment, it is assumed that the objective optical system 2 shown in FIG. 3A is the same as the reference objective optical system 2 'shown in FIG.

  The inverted microscope 1 according to the present embodiment has a shorter focal length Fntl of the imaging optical system 3 than the reference imaging optical system 3 '. As a result, the magnification of the imaging optical system 3 is reduced, and the intermediate image B by the imaging optical system 3 is reduced, whereby the beam diameter when passing through the binocular tube 5 can be reduced. As a result, there is an advantage that the size of the binocular branching prism 18 in the binocular tube 5 can be reduced, and the binocular tube 5 can be reduced in size.

  Furthermore, according to the inverted microscope 1 according to the present embodiment, the focal length Fne of the eyepiece optical system 4 is shortened, and the total magnification of the imaging optical system 3 and the relay optical system 6 is decreased at the same ratio. Thereby, the total magnification of the inverted microscope 1 does not change. Although the image height of the intermediate image C is K times the image height of the intermediate image C ′, the heights of the virtual images D and D ′ viewed with the eyes (E) are equal, and the number of fields can be made substantially the same. . The fact that the number of fields of view is substantially the same means that the viewing angle 2ω ′ of the reference eyepiece optical system 4 ′ and the viewing angle 2ω of the eyepiece optical system 4 are the same.

  In the inverted microscope 1 according to the present embodiment, the above-described coefficient K is set to 0.3 <K <0.9. This is because, when K ≦ 0.3, the focal length of the imaging optical system becomes too short to sufficiently secure the air-converted optical path length before the left and right branches in the binocular tube, or the relay optical system This is because the design becomes difficult because the magnification becomes too small. Further, when K ≧ 0.9, the prism cannot be substantially reduced in size.

Here, it is further preferable to satisfy the following conditional expression.
15 <FN <22 (4)
Here, FN is the number of fields of the eyepiece optical system 4 and is equal to the diameter of the intermediate image C.

Furthermore, it is preferable that the following conditional expression is satisfied.
0.45 <K (5)
By doing so, the focal length of the eyepiece optical system can be increased compared to the case where K ≦ 0.45, and the coma aberration characteristic of the eyepiece optical system is improved.

Furthermore, it is preferable that the following conditional expression is satisfied.
140 <Fntl <210 (6)
0.55 <βRL <1.1 (7)
8 <Fne <23 (8)

  It should be noted that there are some optical systems that include a relay system in the imaging optical system because the optical path needs to be extended in order to incorporate the mechanism in the tilt angle variable lens barrel and the lens barrel for lowering the eye point of the eyepiece, but objective optics The present invention can be applied by regarding an optical system between the system and the eyepiece optical system as an imaging optical system.

(First embodiment)
Next, a first example of the inverted microscope 1 according to the first embodiment of the present invention will be described below. The lens configuration of the inverted microscope 1 according to this example is shown in FIG. 4, the lens data is shown in Table 1, and the aberration diagram is shown in FIG. The prism of the binocular tube 5 is included in the surface interval of surface number 36 in terms of air. In FIG. 4, only part of the surface numbers are shown and others are omitted.

  5A shows field curvature (astigmatism), FIG. 5B shows distortion, FIG. 5C shows off-axis lateral aberration (coma aberration, lateral chromatic aberration), and FIG. 5D shows spherical aberration. Each aberration indicates an aberration calculated by attaching an ideal lens having a focal length of 25 mm instead of the eye E behind the eyepiece optical system 4.

[Table 1]
Surface number Curvature radius Surface spacing Refractive index Abbe number Object surface ∞ 0.17 (cover glass) 1.521 56
1 ∞ 3.59 (WD)
(Objective optical system 2)
2-11.16 6.3 1.6935 53.2
3 ∞ 4.5 1.4343 94.8
4- 10.14 0.18
5 12.98 4.05 1.4343 94.8
6-14.35 0.18
7 11.31 4.5 1.4338 95.0
8-10.04 7.02 1.72 50.3
9 12.18 2.97
10-5.69 0.9 1.5725 57.7
11 112.56 2.07 1.4978 82.6
12 -10.77 0.18
13-139.45 6.75 1.7859 44.2
14-17.46 0.45
15 545.57 1.8 1.6228 57.0
16 16.13 4.05 1.4978 82.6
17 -42.23 102
(Imaging optical system 3)
18 135.09 4.8 1.497 81.5
19-49.98 4.0 1.8044 39.6
20-85.54 161.92
(Relay optical system 6)
21 78.79 5.5 1.6031 60.6
22 -37.35 2.9 1.8052 25.4
23-112.22 4.38
24 21.27 7.67 1.744 44.8
25 ∞ 3.3 1.741 52.6
26 15.46 114.89
27-197.29 2.98 1.5085 61.2
28 38.36 4.9
29 48.8 7.88 1.456 90.3
30 -31.16 3.15 1.5085 61.2
31 -42.51 31.3
32 57.999 3.17 1.4875 70.2
33 294.37 0.35
34 34.35 6.33 1.7234 38.0
35-95.99 2.74 1.7185 33.5
36 27.37 165.67
(Eyepiece optical system 4)
37 ∞ 3.84 1.7859 44.2
38 -25.0 3.95
39 -17.02 2.25 1.8052 25.4
40 31.5 5.92 1.6516 58.5
41 -31.5 0.14
42 80.44 3.6 1.744 44.8
43 -47.22 0.14
44 23.58 4.32 1.5688 56.4
45 ∞

K = 0.8
Fntl = 144
Ftl = 180
βRL = 1.0
Fne = 20
Fe = 25
FN = 20
2ω = 53.1 °
Fob = 18
M ′ = Ftl / Fob × 250 / Fe = 100
M = Fntl / Fob × βRL × 250 / Fne = 100

  Here, K: coefficient, Fntl: focal length of the imaging optical system 3, Ftl: focal length of the reference imaging optical system having a magnification of 1, βRL: magnification of the relay optical system, Fne: eyepiece optical system 4 Focal length, Fe: focal length of reference eyepiece optical system 4 ′ in inverted microscope 1 ′ having reference imaging optical system 3 ′ and reference objective optical system 2 ′, FN: eyepiece optical system 4 equal to the diameter of intermediate image C 2ω: viewing angle of the eyepiece optical system 4, M: total magnification of the inverted microscope 1 of this embodiment, Fob: focal length of the objective optical system 2 and the reference objective optical system 2 ′, M ′: reference objective optical system This is the total magnification of an inverted microscope 1 ′ having 2 ′, a reference imaging optical system 3 ′, and a reference eyepiece optical system 4 ′.

(Second embodiment)
Next, a second example of the inverted microscope 1 according to the first embodiment of the present invention will be described below.
FIG. 6 shows the lens configuration of the inverted microscope 1 according to the present example, Table 2 shows lens data, and FIG. 7 shows aberration diagrams. The prism of the binocular tube 5 is included in the surface interval of the surface number 31 in terms of air. In FIG. 6, only part of the surface numbers are shown and others are omitted.

  7A shows field curvature (astigmatism), FIG. 7B shows distortion, FIG. 7C shows off-axis lateral aberration (coma aberration, lateral chromatic aberration), and FIG. 7D shows spherical aberration. Each aberration indicates an aberration calculated by attaching an ideal lens having a focal length of 25 mm instead of the eye E behind the eyepiece optical system 4.

[Table 2]
Surface number Curvature radius Surface spacing Refractive index Abbe number Object surface ∞ 0.17 (cover glass) 1.521 56
1 ∞ 22.86 (WD)
(Objective optical system 2)
2 55.38 3.44 1.497 81.5
3 -26.01 0.24
4 15.43 4.43 1.6679 55.3
5-52.53 1.62 1.5317 48.9
6 10.57 6.37
7 -10.02 1.75 1.5955 39.2
8 111.49 5.18 1.497 81.5
9-20.91 0.72
10 -52.75 2.68 1.4875 70.2
11 -21.88 0.56
12 -52.75 2.68 1.4875 70.2
13-21.88 102
(Imaging optical system 3)
14 187.63 6.67 1.497 81.5
15-69.42 5.56 1.8044 39.6
16-118.8 217.57
(Relay optical system 6)
17 78.79 5.5 1.6031 60.6
18-37.35 2.9 1.8052 25.4
19-112.22 4.38
20 21.27 7.67 1.744 44.8
21 ∞ 3.3 1.741 52.6
22 15.46 114.89
23 -197.29 2.98 1.5085 61.2
24 38.36 4.9
25 48.8 7.88 1.456 90.3
26 -31.16 3.15 1.5085 61.2
27 -42.51 12.53
28 ∞ 18.77
29 167.48 5.79 1.4875 70.2
30-60.93 3.8 1.7185 33.5
31-106.39 161.61
(Eyepiece optical system 4)
32 -22.29 2.28 1.8052 25.4
33 -14.64 1.07 1.5163 64.1
34 22.29 17.15
35-43.68 5.0 1.755 52.3
36-21.78 0.29
37 ∞ 1.79 1.8052 25.4
38 36.41 7.85 1.7292 54.7
39 -49.98 0.29
40 49.98 7.85 1.7292 54.7
41 -36.41 1.79 1.8052 25.4
42 ∞ 0.29
43 21.78 3.57 1.755 52.3
44 43.68

K = 0.5
Fntl = 200
Ftl = 360
βRL = 0.9
Fne = 12.5
Fe = 25
FN = 16
2ω = 65.2 °
Fob = 36
M ′ = Ftl / Fob × 250 / Fe = 100
M = Fntl / Fob × βRL × 250 / Fne = 100

  Here, K: coefficient, Fntl: focal length of the imaging optical system 3, Ftl: focal length of the reference imaging optical system having a magnification of 1, βRL: magnification of the relay optical system, Fne: eyepiece optical system 4 Focal length, Fe: focal length of reference eyepiece optical system 4 ′ in inverted microscope 1 ′ having reference imaging optical system 3 ′ and reference objective optical system 2 ′, FN: eyepiece optical system 4 equal to the diameter of intermediate image C 2ω: viewing angle of the eyepiece optical system 4, M: total magnification of the inverted microscope 1 of this embodiment, Fob: focal length of the objective optical system 2 and the reference objective optical system 2 ′, M ′: reference objective optical system This is the total magnification of an inverted microscope 1 ′ having 2 ′, a reference imaging optical system 3 ′, and a reference eyepiece optical system 4 ′.

(Other embodiments)
The inverted microscope 1 according to the first embodiment shortens the focal length Fntl of the imaging optical system 3 as compared with the reference imaging optical system 3 ′ having a magnification of 1 ×. May be. Specifically, the focal length Fntl of the imaging optical system 3 may be the same as the focal length Ftl of the reference imaging optical system 3 ′. In this case, in order to satisfy the conditional expressions (1) to (3) according to the first embodiment, the magnification βRL of the relay optical system 6 is reduced.

  By doing so, the focal length of the eyepiece optical system is shortened and the magnification is increased compared to an inverted microscope having a reference imaging optical system and a reference eyepiece optical system with a magnification of 1 ×, and the objective is increased at the same rate. The total magnification of the optical system 2, the imaging optical system 3, and the relay optical system 6 is reduced. Accordingly, even in this case, the number of fields of view of the eyepiece optical system 4 can be made substantially the same without changing the overall magnification of the inverted microscope 1 '. Further, the binocular tube 5 can be reduced in size by reducing the diameter of the light beam when passing through the binocular tube 5.

  In the first embodiment, the objective optical system 2 shown in FIG. 3 (a) is the same as the reference objective optical system shown in FIG. 3 (b). Specifically, the magnification of the reference objective optical system 2 ′ shown in FIG. 3B may be different from the magnification of the objective optical system 2 shown in FIG. In this case, as compared with an inverted microscope having a reference imaging optical system and a reference eyepiece optical system having a magnification of 1 ×, the focal length of the eyepiece optical system is shortened to increase the magnification, and the objective optical system 2 and The total magnification of the imaging optical system 3 and the relay optical system 6 is reduced. In this way, the number of fields of view can be made substantially the same while shortening the overall length of the eyepiece optical system 4 without changing the overall magnification of the inverted microscope 1. Further, the binocular tube 5 can be reduced in size by reducing the diameter of the light beam when passing through the binocular tube 5.

A Sample B Intermediate image C Intermediate image D Virtual image E Eye OA Optical axis ω One-sided angle of viewing angle of eyepiece optical system 1,1 ′ Inverted microscope 2 Objective optical system 2 ′ Reference objective optical system 3 Imaging optical system 3 ′ Reference imaging Optical system 4 Eyepiece optical system 4 'Reference eyepiece optical system 5, 5' Binocular tube (light branching section)
6 Relay optical system 6 'Reference relay optical system 7 Illumination optical system

Claims (4)

An objective optical system for collecting light from the sample;
An imaging optical system for forming light from the sample collected by the objective optical system as an intermediate image;
A relay optical system that relays the intermediate image formed by the imaging optical system;
An optical branching unit for branching light from the relay optical system;
A pair of eyepiece optical systems for enlarging the intermediate image branched by the light branching section to form a virtual image in the eyes of the observer;
An inverted microscope that satisfies the following conditional expression.
K = (Fntl / Ftl) × βRL (1)
Fne = Fe × K (2)
0.3 <K <0.9 (3)
here,
K: coefficient Fntl: focal length of the imaging optical system,
Ftl: Focal length of the reference imaging optical system having a magnification of 1 ×
βRL: magnification of the relay optical system,
Fne: focal length of the eyepiece optical system,
Fe: focal length of an eyepiece optical system in an inverted microscope comprising the reference imaging optical system and the reference objective optical system,
It is. The inverted microscope according to claim 1, which satisfies the following conditional expression.
15 <FN <22 (4)
Here, FN is the number of fields of view of the eyepiece optical system. The inverted microscope according to claim 1 or 2, wherein the following conditional expression is satisfied.
0.45 <K (5) The inverted microscope according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
140 <Fntl <210 (6)
0.55 <βRL <1.1 (7)
8 <Fne <23 (8)

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